quoted from my text book:
F = GMm/r^2
"where r is the distance apart from their centres"
g = F/m = - GM/r^2
Using the equation above, calculate a value for the mass of the Earth (radius of Earth = 6.38 x 10^6m)
M = gr^2/G = 9.81 x (6.38 x 10^6)^2 / 6.67 x 10^-11
... i thought r represented the distance from the centre of two masses (NOT the radius of an object?)
newton's law of gravitation confusion Watch
- Thread Starter
- 08-12-2010 18:26
- 08-12-2010 20:48
Hello Maths guy
In this "g" is the acceleration due to gravity on the surface of earth.
now if you place a point particle of unit mass (m) on the surface of the earth (M), the distance between the two masses = radius of Earth. I hope this clarifies.